问题描述
我想通过HashMap在DBHelper Class中查看多列ListView中的记录。这将显示我的数据在多列和所有行都是可点击的。我有一些困难。我的代码在这里
DBHelper.java
public ArrayList< HashMap< ; String，String>> getdata（）{
ArrayList< HashMap< String，String>> maplist = new ArrayList< HashMap< String，String>>（）;
SQLiteDatabase db = getReadableDatabase（）;
String query =select * from tbexpenses;
Cursor c = db.rawQuery（query，null）;
if（c.moveToFirst（））{
do {
HashMap< String，String> map = new HashMap< String，String>（）;
for（int i = 0; i< c.getColumnCount（）; i ++）{
map.put（c.getColumnName（i），c.getString（i））;
}
} while（c.moveToNext（））;
} db.close（）;
返回地图列表;
}
ListView.java
package com.multiplecolumnlist;
import java.util.ArrayList;
import java.util.HashMap;
导入android.app.Activity;
导入android.os.Bundle;
导入android.view.Menu;
导入android.view.MenuItem;
导入android.view.View;
导入android.widget.AdapterView;
导入android.widget.ListView;
导入android.widget.Toast;
import static com.multiplecolumnlist.Constants.FIRST_COLUMN;
import static com.multiplecolumnlist.Constants.FOURTH_COLUMN;
import static com.multiplecolumnlist.Constants.SECOND_COLUMN;
import static com.multiplecolumnlist.Constants.THIRD_COLUMN;
public class MainActivity extends Activity {
$ b $ private ArrayList< HashMap< String，String>>列表;
@Override
protected void onCreate（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）;
setContentView（R.layout.activity_main）;
ListView listView =（ListView）findViewById（R.id.listView1）;
list = new ArrayList< HashMap< String，String>>（）;
??????????????????????????????????????????????????????? ???
ListViewAdapters adapter = new ListViewAdapters（this，list）;
listView.setAdapter（adapter）;
listView.setOnItemClickListener（new AdapterView.OnItemClickListener（）
{
@Override
public void onItemClick（AdapterView<？> parent，final View view，int position ，long id）
{
int pos = position + 1;
Toast.makeText（MainActivity.this，Integer.toString（pos）+Clicked，Toast.LENGTH_SHORT）.show（ ）;
}
}）;
$ b ListViewAdapter.java
public class ListViewAdapters extends BaseAdapter {
$ b $ public ArrayList< HashMap< String，String>>列表;
活动活动;
TextView txtFirst;
TextView txtSecond;
TextView txtThird;
TextView txtFourth;
public ListViewAdapters（Activity activity，ArrayList< HashMap< String，String>> list）{
super（）;
this.activity = activity;
this.list = list;
$ b $ @Override
public int getCount（）{
// TODO自动生成的方法存根
return list.size（）;
$ b @Override
public Object getItem（int position）{
// TODO自动生成的方法存根
return list.get（position） ;
}
@Override
public long getItemId（int position）{
// TODO自动生成的方法存根
return 0;
$ b @Override
public View getView（int position，View convertView，ViewGroup parent）{
// TODO Auto-生成的方法存根
LayoutInflater inflater = activity.getLayoutInflater（）;
if（convertView == null）{
convertView = inflater.inflate（R.layout.column_row，null）;
txtFirst =（TextView）convertView.findViewById（R.id.name）;
txtSecond =（TextView）convertView.findViewById（R.id.gender）;
txtThird =（TextView）convertView.findViewById（R.id.age）;
txtFourth =（TextView）convertView.findViewById（R.id.status）;
}
HashMap< String，String>地图= list.get（位置）;
txtFirst.setText（map.get（FIRST_COLUMN））;
txtSecond.setText（map.get（SECOND_COLUMN））;
txtThird.setText（map.get（THIRD_COLUMN））;
txtFourth.setText（map.get（FOURTH_COLUMN））;
返回convertView;
}
}
Constant.java
public class Constants {
public static final String FIRST_COLUMN =First;
public static final String SECOND_COLUMN =Second;
public static final String THIRD_COLUMN =Third;
public static final String FOURTH_COLUMN =Fourth;
}
解决方案 list.clear（）;
DBHelper helper = new DBHelper（）;
list = helper.getdata（）;
编辑1：中的错误getdata（）
检查您的 getdata（）函数
public ArrayList< HashMap< String，String>> getdata（）{
ArrayList< HashMap< String，String>> maplist = new ArrayList< HashMap< String，String>>（）;
SQLiteDatabase db = getReadableDatabase（）;
String query =select * from tbexpenses;
Cursor c = db.rawQuery（query，null）;
if（c.moveToFirst（））{
do {
//你在这里创建映射，但不把这个映射添加到列表
HashMap< String，String> map = new HashMap< String，String>（）;
for（int i = 0; i< c.getColumnCount（）; i ++）{
map.put（c.getColumnName（i），c.getString（i））;
}
//所以在这里添加它
maplist.add（map）;
} while（c.moveToNext（））;
}
db.close（）;
返回地图列表;
}
然后运行正常。
I want to View my record in Multicolumn ListView From DBHelper Class by HashMap. that will show my data in multicolumn and also all rows are clickable. i have some difficulty. my code is here
DBHelper.java
public ArrayList<HashMap<String, String>> getdata(){
ArrayList<HashMap<String, String>> maplist = new ArrayList<HashMap<String,String>>();
SQLiteDatabase db = getReadableDatabase();
String query = "select * from tbexpenses";
Cursor c = db.rawQuery(query, null);
if(c.moveToFirst()){
do{
HashMap<String, String> map = new HashMap<String, String>();
for(int i=0; i<c.getColumnCount();i++){
map.put(c.getColumnName(i), c.getString(i));
}
}while (c.moveToNext());
}db.close();
return maplist;
}
ListView.java
package com.multiplecolumnlist;
import java.util.ArrayList;
import java.util.HashMap;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.Toast;
import static com.multiplecolumnlist.Constants.FIRST_COLUMN;
import static com.multiplecolumnlist.Constants.FOURTH_COLUMN;
import static com.multiplecolumnlist.Constants.SECOND_COLUMN;
import static com.multiplecolumnlist.Constants.THIRD_COLUMN;
public class MainActivity extends Activity {
private ArrayList<HashMap<String, String>> list;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ListView listView=(ListView)findViewById(R.id.listView1);
list=new ArrayList<HashMap<String,String>>();
?????????????????????????????????????????????
ListViewAdapters adapter=new ListViewAdapters(this, list);
listView.setAdapter(adapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener()
{
@Override
public void onItemClick(AdapterView<?> parent, final View view, int position, long id)
{
int pos=position+1;
Toast.makeText(MainActivity.this, Integer.toString(pos)+" Clicked", Toast.LENGTH_SHORT).show();
}
});
}
ListViewAdapter.java
public class ListViewAdapters extends BaseAdapter{
public ArrayList<HashMap<String, String>> list;
Activity activity;
TextView txtFirst;
TextView txtSecond;
TextView txtThird;
TextView txtFourth;
public ListViewAdapters(Activity activity,ArrayList<HashMap<String, String>> list){
super();
this.activity=activity;
this.list=list;
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return list.size();
}
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return list.get(position);
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
LayoutInflater inflater=activity.getLayoutInflater();
if(convertView == null){
convertView=inflater.inflate(R.layout.column_row, null);
txtFirst=(TextView) convertView.findViewById(R.id.name);
txtSecond=(TextView) convertView.findViewById(R.id.gender);
txtThird=(TextView) convertView.findViewById(R.id.age);
txtFourth=(TextView) convertView.findViewById(R.id.status);
}
HashMap<String, String> map=list.get(position);
txtFirst.setText(map.get(FIRST_COLUMN));
txtSecond.setText(map.get(SECOND_COLUMN));
txtThird.setText(map.get(THIRD_COLUMN));
txtFourth.setText(map.get(FOURTH_COLUMN));
return convertView;
}
}
Constant.java
public class Constants {
public static final String FIRST_COLUMN="First";
public static final String SECOND_COLUMN="Second";
public static final String THIRD_COLUMN="Third";
public static final String FOURTH_COLUMN="Fourth";
}
解决方案 replace this code with question mark
list.clear();
DBHelper helper = new DBHelper();
list = helper.getdata();
EDIT 1:Error in getdata() method
Also check your getdata() function
public ArrayList<HashMap<String, String>> getdata(){
ArrayList<HashMap<String, String>> maplist = new ArrayList<HashMap<String,String>>();
SQLiteDatabase db = getReadableDatabase();
String query = "select * from tbexpenses";
Cursor c = db.rawQuery(query, null);
if(c.moveToFirst()) {
do {
// you are creating map here but not adding this map to list
HashMap<String, String> map = new HashMap<String, String>();
for(int i=0; i<c.getColumnCount();i++) {
map.put(c.getColumnName(i), c.getString(i));
}
// so do add it here
maplist.add(map);
} while (c.moveToNext());
}
db.close();
return maplist;
}
Then it'll run fine.
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